The coordinates are periodically extracted from Wikipedia articles. Clicking on a marker takes you to the article it was extracted from. This can either be the article with the same title as the marker reads, or you might end up in a List-Article with lots of coordinates (For example "List of Capitals in Afrca" (I just made that up)). Make sure all instances of coordinates either in the Addis Abeba article, or potential coordinates labled 'Adid Abbeba' on other pages have the same latituded and longitudes.
Sometimes there are multiple coordinates in one article which should point to the same location but they don't. That obviously needs to be fixed (somtimes some of the coordinates are in DMS, and others in decimal degrees). Data duplication should be avoided, and in my opinion it is safest to delete duplicate coordinates (especially if they are wron, rather than fixing them).
Hope this helps, let me know.